Varisable maximum throttle position for engine



Nov. 17, 964 B. WALKER ETAL 3,157,157

VARIABLE MAXIMUM THROTTLE POSITION FOR ENGINE Filed Feb. 15, 1961 INVENTORS BROOKS WALKER BYFRED v. HALL United States Patent Ofiice 3,157,167 VARIABLE MAXIMUM THROTTLE PQEHTHGN FOR ENGINE Brooks Walker and Fred V. Hail, both of 12% Qolumbus Ave, San Francisco 11, @alif. Filed Feb. 13, 1961, Ser. No. 83,867 4 Claims. ((1 123-103) This invention relates to a device to control the throttle of an internal combustion engine. More particularly it relates to a device to control the throttle opening in proportion to engine speed to limit engine operation in such a fashion that efiicient combustion is maintained at all times and the smog forming pollutants (principally hydrocarbons and carbon monoxide) in the exhaust are minimized.

The Hall patent (No. 2,809,623) provides various controls for an internal combustion engine to reduce to a minimum hydrocarbons and carbon monoxide in the exhaust. Among these is a throttle stop which limits throttle opening to eliminate or substantially reduce engine operation under conditions where the power enrichment feature of the carburetor is activated. It is desirable to eliminate this type of operation because the extremely rich mixture produces excessive exhaust pollutants. It is therefore the primary objective of the present invention to solve this problem; however, through the use of a novel combination of elements a secondary objective is achieved. The secondary objective which is of great importance is to allow maximum engine performance consistent with the requirements for clean burning in the combustion chamber of the engine.

The invention solves the problem of limiting full throttle operation to conditions of clean burning but allows near maximum horsepower at all engine speeds. This is accomplished principally by the use of a variable throttle stop mechanism responsive to engine speed. This allows more throttle opening at high engine speed and less at low engine speed because with a fixed throttle stop position a higher degree of vacuum occurs at high engine speed. As the power enrichment feature may bevacuum controlled less throttle opening can be tolerated at low speed as compared to high speed to prevent the power valve from coming in.

Conventional governor mechanisms while suitable for their intended purpose do not control the engine operation to obtain clean burning at all throttle/speed conditions. These generally either limit top engine speed or mass air flow to the engine and are designed primarily to improve fuel economy and/ or engine durability.

It is also an obiective of the present invention to vary the maximum throttle opening with speed in conformance with the lean mixture (clean burning) octane requirement of the engine.

Another objective of this invention is to minimize the necessary restriction for clean burning in the engine in order that maximum performance of the vehicle is available consistent with minimum exhaust pollutants.

Another object of the invention is to provide a hydraulic control where the hydraulic pressure varies at less than the square of the engine yield to more easily control a stop cam operated by said varying hydraulic pressure or to control any other engine control.

Other objects and advantages of the invention will appear from the following description of a preferred embodiment and appended claims, reference being had to accompanying drawings forming a part of this specification wherein like reference characters designate cor-' engine, its carburetor, exhaust, and intake manifolds,

auras? Patented Nov. 17, 1964 throttle linkage, etc. together with a preferred embodiment of the present invention, part of the manifold being shown cut away.

FIG. 2 is an enlarged view in elevation and section of the diaphragm device which actuates the throttle stop.

FIG. 3 is similar to FIG. 2 but with the diaphragm and cam throttle stop in the position of high engine speed.

FIG. 4 is an enlarged elevational view, partly in section of the hydraulic pump, hydraulic oil supply tank, restriction valve and hydraulic lines as used in FIG. 1.

FIG. 5 shows a partial section through the lines 5-5 of FIG. 4.

FIG. 6 is similar to FIG. 4 but with a porous mediatype of resistance rather than an orifice-type.

FIG. 1 shows a gasoline engine 19 together with pertinent systems associated with this invention. The throttle pedal 11 is connected to rod 12 and double lever 13 and to one end of spring 14. The other end of spring 14 is attached to lever 15 to which rod 15 is secured. Rod 16 is urged toward the closed throttle position by spring 17 attached at one end to rod 16 by bracket 18 and to carburetor bowl 19 at the opposite end. Rod 16 also actuates throttle bell crank 26 and throttle stop lever 21. A damping means, such as dash pot 9, like that shown in Hall Patent 2,809,623, is preferably connected to a suitable part of the lever system, such as the lever 21. Carburetor air cleaner 22 and throttle butterfly 23 are shown in their relative positions for reference purposes. Also exhaust manifold 24, intake manifold 25, exhaust pipe 26, crankcase pan 27, engine cooling fan 28, fan belt 29, drive pulley 3d are shown for orientation as are cylinder head 31 and rocker arm cover 32. Bracket 33 mounted on rocker arm cover 32 carries hydraulic actuating device 34, throttle stop cam 35, and throttle stop lever 21.

Hydraulic actuating device 34 is connected by metal tube 36, rubber tube 37, metal tube 38 and T fitting 39 to the discharge side of hydraulic pump 4-0 and to restriction valve 41. Tube 42 leads from oil supply tank 4-3 to the suction side of hydraulic pump 40. Tube 4 2a leads from restriction valve 41 to oil supply tank 43. Supply tank 4-3 is filled through filler/breather cap 44. Hydraulic pump 49 is attached by shaft 4-5 to drive pulley 46 which is driven by fan belt 29.

FIGURE 2 shows additional details of hydraulic actuating device 34 in which flexible diaphragm 47 presses downward the enlarged head of push rod 48 which is within threaded portion 5% of hydraulic actuator 34. Throttle stop cam 35 is rigidly attached to the lower end of push rod 48 and slides on guide pin 51 in slot 52. The pin 51 is attached to the bracket 33 and thereby assures vertical movement of the cam 35.

Hydraulic pump gears 53 and 53a (FIG. 4) are driven by pulley 46 by means of shaft 45. Needle valve 54 controls flow through restriction valve .1.

' the closed throttle position and the maximum opening position determined by roller 21a contacting the lower face of cam 35 which is opposite roller 21a at low engine speed. At low engine speed the oil pressure from pump 41? through restriction valve 41 is low, so diaphragm 47 is' up, as shown in FIG. 2 due to the action of spring all o 49. The driver may then tramp down on throttle pedal 11 to accelerate the vehicle or to maintain speed uphill. When he does this throttle stop lever 21 contacts throttle stop cam 35 which limits the throttle opening to a position substantially less than full throttle. his position generally would be determined by the low speed, lean mixture no noise (ping, detonation, etc.) octane requirement for the particular engine speed. The vehicle now accelerates and the engine speed increases. The increase in engine speed normally would cause the manifold vacuum to increase (lower pressure) but as the engine speed increases so does the pressure delivered by hydraulic pump as due to the resistance to increased flow by valve 41 or restrictor er. The increased pressure is transmitted through tubes 33, 3'7, and 36 to hydraulic actuating device 34. As a result throttle stop cam 35' is raised at low speed and lowered at high speed at a rate depending on the speed pressure relationship due to increased flow past valve 41 or restrictor 61. The contour of throttle stop cam 35 can be designed to follow the desired engine parameters for lean mixture knock-free operation at operating engine speeds with smog control operation. The cam contour can also be such as to prevent completely or almost completely the operation of the power valve in the carburetor. Thus, relatively clean burning, lean mixture conditions are maintained at all times or substantially at all times even when the accelerator pedal is tioorhoarded as compared to the operation without such a throttle stop.

To further illustrate how the proposed invention operates, I have shown in FIG. 6 the operation at high speed when the oil pressure is high due to the increased resistance to increased flow past restrictor valve 41 in which the pressure may rise somewhere near the square of the engine speed. The increase in the oil pressure with an increase in engine speed can be at a lower rate if desired by using the restrictor in container oil in which case the discharge from pump 49 increases substantially in proportion to engine speed due to the degree of restriction of restrictor in restrictor container 69 located between T39 and line 420, as shown in FIG. 7. This restrictor can be one or more holes through a block 61 or a series of passages through sintered bronze or other porous media. With a restrictor of the sintered bronze type or porous media type laminar iiow is maintained and the increase in oil pressure when the discharge of the pump is substantially in proportion to the engine pressure may be a more direct (linear) function of the engine speed rather than increasing at the higher rate which would be required to force the oil through valve 41 under turbulent flow conditions. With the higher oil pressure at high speed, the diaphragm will be forced down against spring 49 and cam 35 will approach or reach its lowest position at or near high engine speeds. At these higher engine speeds the velocity flow resistance of the gases through the carburetor, the manifold, the intake valves, etc. results in a higher partial vacuum at the end of the intake stroke than prevails at lower engine speed when such losses are less. In order to be able to have about the same maximum compression pressure at the end of the compression stroke it is desirable to increase the maximum allowable throttle opening at higher engine speeds when the operators foot is tramped down on the accelerator pedal 11. This is accomplished by the cam 35 moving down allowing throttle stop lever 21 to rotate a certain amount counterclockwise to increase the maximum opening of butterfly 23 in carburetor 1. If a hill is encountered while the throttle is still held open and the engine speed is reduced materially to down near a relatively low engine speed, the oil pressure above diaphragm 47 will be substantially reduced and spring 49 will raise cam 35. Throttle stop lever 21 will be forced in a partial clockwise rotation to partially close butterfly 23 to an extent that will keep the maximum compression pressure at maximum throttle opening, as determined by this doice, from increasing excessively at the lower speeds. The face of the cam 35 that bears against roller 21a of throttle stop lever 21 can vary in any desired contour that will give the most desired results during the open throttle operation over a wide range of engine speed changes. This is possible through the action of the soft link or spring 14 between the throttle pedal, rod 12, and rocker arm.

To those skilled in the art to which this invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

We claim as our invention:

1. An engine throttle system comprising a carburetor having a throttle valve,

lever means connected to and controlling closure of said valve,

a variable-position stop means engaged by said lever means after limited movement thereof tending to open said throttle valve thereby controlling the maximum opening of said throttle valve,

a positive displacement pump driven by said engine in proportion to its speed, and

a hydraulic system connecting said pump to said stop means for changing the position of said stop means and in accordance with the increase in engine speed, so that the higher the engine speed, the greater the throttle opening permitted by said variable-position stop means,

said hydraulic system having porous media type restriction means in said hydraulic system so that the discharge from said pump asses through said porous media before returning to said pump to cause the pressure from said pump to increase at a rate substantially less than proportional to the square of the engine speed.

2. An engine throttle system comprising a carburetor having a throttle valve,

lever means connected to and controlling opening and closure of said valve,

stop means having a carnmed surface adapted to be engaged by said lever means to prevent further movement thereof tending to open said throttle valve, thereby controlling the maximum opening of said throttle valve,

a diaphragm to which said stop means is connected for movement therewith and consequent changing of the portion of said camrned surface engaged by said lever means and therefore changing the maximum opening or" said throttle valve,

biasing means exerting pressure on said diaphragm normally tending to move said cammed surface to a position where it permits only a minimum opening of said throttle valve,

pump means mechanically driven by the engine in direct linear proportion to its speed,

a hydraulic system connected through said pump means to the opposite side of said diaphragm from said stop means for providing hydraulic liquid for overcoming said biasing means by hydraulic pressure that increases with the increase in engine speed, so that the higher the engine speed, the greater the throttle opening permitted by said stop means, and

porous media restriction means in said hydraulic sysem for increasing the pressure on said diaphragm in substantially linear proportion to the engine speed.

3. An engine throttle system comprising a carburetor having a throttle valve,

first lever means connected to and controlling opening and closure of said valve,

damping means connected to said lever means,

second lever means pivotal-1y connected at one end to said first lever means and having a second end and a stationary pivot between said ends,

stop means having a cammed surface adapted to be engaged by said second end to prevent further swinging of said second lever means and therefore preventing further movement of said first lever means tending to open said throttle valve, thereby controlling the maximum opening of said throttle valve,

a diaphragm to which said stop means is connected for movement therewith and consequent changing of the portion of said cammed surface engaged by said second end and therefore changing the maximum opening of said throttle valve,

biasing means exerting pressure on said diaphragm normally tending to move said cammed surface to a position where it permits only a minimum opening of said throttle valve,

positive displacement pump means driven by said engine in direct linear proportion to its. speed,

a source of hydraulic liquid connected through said pump means to the opposite side of said diaphragm from said step means for overcoming said'biasing means by hydraulic pressure that increases with the increase in engine speed, so that the higher the engine speed, the greater the throttle opening permitted by said stop means, and

said porous media restriction means connected to conduit means for returning liquid from said pump to said source and thereby to govern the pressure thereof acting on said diaphragm so that said pressure is in substantially direct linear proportion to engine speed.

4. A variable pressure actuated device, an engine, a Variable pressure sounce, said variable pressure source developed by a substantially positive displacement pump driven in proportion to engine speed, a reservoir, a porous medium through which the discharge of said pump is driven at any given engine speed to produce a different pressure at different engine speeds to actuate said device, said device controlling a function of said engine operation, conduits conducting the discharge from said pump to said device and to said porous medium, other conduits conducting fluid from said porous medium to said reservoir, still other conduits conducting fluid from said reservoir to the intake side of said pump.

References Cited in the file of this patent UNITED STATES PATENTS 783,679 Caille Feb. 28, 1905 1,222,985 Pharo Apr. 17, 1917 1,358,812 Anderson Nov. 16, 1920 2,260,576 Maybach Oct. 28, 1941 2,293,842 Mallory Aug. 25, 1942 2,361,206 Hoppe Oct. 24, 1944 2,507,415 Mallory May 9, 1950 2,517,501 Mennesson Aug. 1, 1950 2,585,814 McDonald Feb. 12, 1952 2,588,136 Mallory Mar. 4, 1952 2,809,623 Hall Oct. 15, 1957 2,815,739 H011 Dec. 10, 1957 2,825,418 Kershman Mar. 4, 1958 2,873,104 Horwood Feb. 10, 1959 

3. AN ENGINE THROTTLE SYSTEM COMPRISING A CARBURETOR HAVING A THROTTLE VALVE, FIRST LEVER MEANS CONNECTED TO AND CONTROLLING OPENING AND CLOSURE OF SAID LEVER MEANS DAMPING MEANS CONNECTED TO SAID LEVER MEANS, SECOND LEVER MEANS PIVOTALLY CONNECTED AT ONE END TO SAID FIRST LEVER MEANS AND HAVING A SECOND END AND A STATIONARY PIVOT BETWEEN SAID ENDS, STOP MEANS HAVING A CAMMED SURFACE ADAPTED TO BE ENGAGED BY SAID SECOND END TO PREVENT FURTHER SWINGING OF SAID SECOND LEVER MEANS AND THEREFORE PREVENTING FURTHER MOVEMENT OF SAID FIRST LEVER MEANS TENDING TO OPEN SAID THROTTLE VALVE, THEREBY CONTROLLING THE MAXIMUM OPENING OF SAID THROTTLE VALVE, A DIAPHRAGM TO WHICH SAID STOP MEANS IS CONNECTED FOR MOVEMENT THEREWITH AND CONSEQUENT CHANGING OF THE PORTION OF SAID CAMMED SURFACE ENGAGED BY SAID SECOND END AND THEREFORE CHANGING THE MAXIMUM OPENING OF SAID THROTTLE VALVE, BIASING MEANS EXERTING PRESSURE ON SAID DIAPHRAGM NORMALLY TENDING TO MOVE SAID CAMMED SURFACE TO A POSITION WHERE IT PERMITS ONLY A MINIMUM OPENING OF SAID THROTTLE VALVE, POSITIVE DISPLACEMENT PUMP MEANS DRIVEN BY SAID ENGINE IN DIRECT LINEAR PROPORTION TO ITS SPEED, A SOURCE OF HYDRAULIC LIQUID CONNECTED THROUGH SAID PUMP MEANS TO THE OPPOSITE SIDE OF SAID DIAPHRAGM FROM SAID STOP MEANS FOR OVERCOMING SAID BIASING MEANS BY HYDRAULIC PRESSURE THAT INCREASES WITH THE INCREASE IN ENGINE SPEED, SO THAT THE HIGHER THE ENGINE SPEED, THE GREATER THE THROTTLE OPENING PERMITTED BY SAID STOP MEANS, AND SAID POROUS MEDIA RESTRICTION MEANS CONNECTED TO CONDUIT MEANS FOR RETURNING LIQUID FROM SAID PUMP TO SAID SOURCE AND THEREBY TO GOVERN THE PRESSURE THEREOF ACTING ON SAID DIAPHRAGM SO THAT SAID PRESSURE IS IN SUBSTANTIALLY DIRECT LINEAR PROPORTION TO ENGINE SPEED. 